XO-1 Exoplanet Transits

The C11 observing XO-1b

Site and Instruments

The measurements were performed with a Celestron 11-inch telescope and a
ST-7E CCD camera at the Polaris Obseratory, where unfortunately the sky
is filled with the “skyglow” of Budapest. The camera is sponsored by the
AAVSO & Curry Foundation.

The exposure times were 20s with 2×2 bining, without using any filter.
With this technique,
we got about 2 measurements pro minute. During these three nigst, a total
of 1050 images were obtained
and processed using IRAF.

The XO-1 exoplanet-system.
Study Sponsored by AAVSO & Curry Foundation.
The stars on the finder chart marked with numbers are
the refenrence stars.


After image preprocessing (dark and flat corrections), computing the
heliocentric Julian date for every image, and registering the images, we
used the qphot task from the daophot.apphot package to
perform the measurements. Since our field of view was very small, we
could used
only two reference stars: those marked with 1 and 3 on the finder


The next figure presents the light curve change of XO-1 during the nights
of June 16/17, 20/21, and 24/25 computed from the captured CCD images.
The x axis shows
the phase of the light change and the y axis represents the differential
magnitude (the unit is 0.01 mag). It is clearly seen, that the
measurements of the first night have a bigger standard deviation due to
the hazy sky.


The phasediagram of XO-1 (GSC 02041-01657) between June 16-25 2006.

For computing the phase, we used P=3,941534 days, the value given by
McCullough, and the epoch is 2453808.917. It can be seen, that
using these values,
the predicted central transit is matching well with 0. With time the
difference between the
actual and computed period is growing, and so the light curves are
shifted a bit. This
difference can be used to refine the period.

Future Work

During this year there will be some more possibilities to observe
the transition of XO-1b. Here you can find the predictad date and
time of transits that can be observed from the Polaris Observatory.


Observation Window
22:52 – 02:04
partially visible
21:28 – 00:40
20:04 – 23:16
18:40 – 21:52
17:15 – 20:27
partially visible
01:57 – 05:11
00:33 – 03:47

All Times UT

The full list of XO-1b can be found here: http://www.ucolick.org/~laugh/XO-1_____b.transits.txt

Tamás Tordai, Emese Balogh, and Zoltán A. Nagy
Polaris Photometry Group